## 实机操作

进入名为 sys 数据库

```mysql
use sys;
```

创建表 person

```mysql
create table person(
 id int not null primary key auto_increment,
 name char(40) not null default '',
 age int not null default 20,
 info char(5) null
 );
```

查看数据

```mysql
desc person;
```

![image-20220315081824424](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315081824424.png)

查看表内数据

```mysql
select * from person;
```

![image-20220315082028785](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315082028785.png)

插入数据

```mysql
insert into person (id,name,age,info)
values(1,'Green',21,'lar');
```

查看数据

![image-20220315082524826](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315082524826.png)

插入数据

```mysql
insert into person (id,age,name,info) values(2,22,'su','do');
```

查看数据

![image-20220315082918594](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315082918594.png)

插入数据

```mysql
insert into person values(3,'wang',23,'ji');
```

查看数据

![image-20220315083226414](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315083226414.png)

插入数据

```mysql
insert into person (age,name,info) values(32,'xu','deo');
```

查看数据

![image-20220315083745218](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315083745218.png)

插入指定字段

```mysql
insert into person (age,name,info) values(32,'xu','deo');
insert into person (name,age)values('wan',23);
insert into person (name)values('win');
```

![image-20220315084255104](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315084255104.png)

插入多条数据

```mysql
insert into person (age,name,info)
values(26,'xi','dreo'),
(22,'ju','do'),
(39,'vheng','dxu');
```

![image-20220315085241890](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315085241890.png)

创建新表

```mysql
create table person2(
 id int not null primary key auto_increment,
 name char(40) not null default '',
 age int not null default 20,
 info2 char(5) null
 );
```

将查询结果插入到表中

```mysql
insert into person2 (id,name,age,info2)
select * from person;
```

![image-20220315090756156](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315090756156.png)、

更新数据

```mysql
 update person set age=15,name='liming' where id=9;
```

![image-20220315092323856](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315092323856.png)

查询语句限制

```mysql
select * from person where id=9;
*是指泛指
select name from person where id=9;
```

![image-20220315092608371](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315092608371.png)

![image-20220315092645199](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315092645199.png)

查询年龄在19到25之间的人

```mysql
select * from person where age between 19 and 25;
```

![image-20220315092906118](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315092906118.png)

删除表中 id 为9的人

```mysql
delete from person where id=9;
```

![image-20220315093201546](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315093201546.png)

删除所有表中数据

```mysql
delete from person;
```

![image-20220315093559445](https://yovinchen-1308133012.cos.ap-beijing.myqcloud.com/image-20220315093559445.png)

## 一、插入数据

### 1.为表的所有字段插入数据

```mysql
insert into 表名 (字段名,字段名,字段名)
values(对应字段的值,对应字段的值,对应字段的值);
```

备注：允许字段名顺序与建表时顺序不同，不需要按照表定义的顺序插入，只要保证值的顺序和前面字段名的顺序相同即可。

例：insert into person (id,age,name,info) values(2,22,'su','do');



备注2：使用insert语句插入数据时，允许将字段名省略，此时注意，值列类表需要为表中的每一个字段赋值，并且值的顺序必须与建表时各个字段的顺序相同。

例：insert into person (id,age,name,info) values(2,22,'su','do');



### 2.为表指定字段插入数据

为表的指定字段插入数据，就是在 insert 语句中指向部分字段插入值，而其他字段的值为表定义时的默认值。

例：insert into person (age,name,info) values(32,'xu','deo');

insert into person (name,age)values('wan',23);

insert into person (name)values('win');

备注：要保证每个插入值的类型和对应字段的数据类型保持一致，否则报错

### 3.同时插入多条数据

insert into 表名 (各个字段名) values(第一条记录的值列表), (第二条记录的值列表), (第三条记录的值列表)

例：

```mysql
insert into person (age,name,info)
values(26,'xi','dreo'),
(22,'ju','do'),
(39,'vheng','dxu');
```

### 4.将查询结果插入到表中

语法：insert into 新表名(字段名)查询语句;**此处没有values**

注意：两个表的数据类型必须一致，字段个数也要一致。

insert into person2 (id,name,age,info2)select * from person;

## 二、更新数据

update 表名 set 需要更新字段名1=值,需要更新的字段名2=值  where 条件;

补充：select 字段名 from 表名 where 条件; 

select * from person where age between 19 and 25;

## 三、删除数据（删除操作是不可逆的删除时一点要小心）

1.有选择删除

语法：delete from 表名 where 限定条件;

例：delete from person where id=9;

2.删除表中所有数据

语法：delete from 表名;